Polyamide resin is widely used in various fields including electrical components, electronics components, and automobile components due to its excellent heat resistance, wear resistance, chemical resistance, and flame retardancy.
Due to the recent trend towards weight reduction in the automobile field, metal components are being replaced by plastic components. Polyamide resin compositions having excellent heat resistance have been used for engine rooms in automobiles which are under the hood areas that are exposed to high temperature environments for long periods of time.
In the automobile field, engines are being down-sized to increase fuel efficiency, leading to an increase of vehicles having turbo chargers. In the case of an automobile using a turbo charger, the temperature inside the under hood increases more rapidly than conventional automobiles when high-powered. Thus, there is a growing need for materials having higher heat resistance for use in components that will be installed inside the under hood so that they can withstand the high temperature environment for long periods of time.
In order to secure long-term heat resistance in a polyamide resin composition, organic antioxidants such as phenol or phosphite compounds are widely used. These organic antioxidants, however, can have limitations in maintaining excellent properties for long periods of time at high temperatures to a satisfying level.
Copper halide thermal stabilizers such as CuI/Ki compounds are also used which are known to have even higher long term thermal stability at high temperatures than organic antioxidants. However, copper may discolor or precipitate as time passes, causing problems when used in electrical, electronic and automobile components.
Therefore, there is a need for a polyamide resin composition that can maintain its high thermal stability even when exposed to high temperatures for long periods of time so that it can be used in components for use in an engine room inside an under hood of an automobile.